Negative Stiffness Inserts for Vibration Damping
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Solution Overview
Problem
Conventional vibration isolation systems face challenges in combining high stiffness and high damping efficiently, often requiring costly and heavy materials, and lack control over microstructures for wide operating conditions, making it difficult to create lightweight, scalable, and temperature-resistant shock absorbers/vibration dampers with optimal structural strength.
Innovation Solution
A vibration control apparatus featuring a core material with embedded positive and negative stiffness structures, where the positive stiffness material includes coils, microtruss structures, or tension wires, and the negative stiffness material consists of dual arms connected to a hub, allowing for enhanced damping and stiffness combinations through bistable mechanisms integrated into traditional core materials like foams or honeycombs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional vibration isolation systems use low stiffness materials to achieve high damping, then damping performance is improved, but structural strength and stiffness are reduced
Solution Approach 1:
The patent employs composite materials combining positive stiffness materials (providing structural strength) and negative stiffness materials (providing enhanced damping). This composite approach allows the system to simultaneously achieve high structural strength and superior damping performance, resolving the contradiction between these two properties that plagues conventional isolation systems.
Solution Approach 2:
The patent utilizes negative stiffness structures that exhibit parameter changes under different loading conditions. These structures can transition between different stiffness states, allowing the material to provide high damping when needed while maintaining structural integrity. This dynamic parameter adjustment enables the system to overcome the static trade-off between stiffness and damping in conventional materials.
2Strength
If solid state damping materials such as piezoelectric and magnetostrictive materials are used to maintain structural stiffness, then stiffness is improved, but cost, weight, and brittleness increase
Solution Approach 1:
The patent employs conventional, cost-effective materials in negative stiffness configurations that can be manufactured using standard processes. Instead of relying on expensive solid state materials like piezoelectric or magnetostrictive materials, the invention uses readily available materials arranged in bistable structures, significantly reducing cost and weight while achieving comparable or superior performance.
Solution Approach 2:
The patent replaces solid state damping materials (piezoelectric, magnetostrictive) with mechanical negative stiffness structures. This substitution eliminates the need for costly, heavy, and brittle solid state materials while achieving the same damping function through purely mechanical bistable structures that are lighter, cheaper, and more ductile.
3Loss of energy
If conventional low stiffness isolation systems are designed to achieve high damping, then damping is improved, but weight and volume increase
Solution Approach 1:
The patent utilizes negative stiffness structures that exhibit large deformations and parameter changes under load, enabling high damping in compact configurations. These bistable structures can absorb significant energy through snap-through transitions, achieving high damping performance in lightweight, space-efficient designs that conventional low-stiffness systems cannot match.
Solution Approach 2:
By combining positive and negative stiffness materials in a composite structure, the patent achieves high damping-to-weight ratio. The negative stiffness components provide enhanced damping in small volumes, while the positive stiffness components maintain structural integrity, creating a lightweight composite system that outperforms conventional isolation materials in specific damping capacity.
4Loss of energy
If negative stiffness structures are used to enhance damping, then damping capacity is improved, but control over microstructures for wide operating conditions becomes challenging
Solution Approach 1:
The patent designs negative stiffness structures with controllable microstructural parameters that can be adjusted to optimize performance for different operating conditions. By varying geometric parameters, material properties, and stacking configurations, the system can be tailored to provide optimal damping across wide temperature ranges and different strain spaces, achieving both high damping capacity and adaptability.
Solution Approach 2:
The patent creates negative stiffness structures with universal design features that enable them to function effectively across diverse operating conditions. The bistable mechanisms are designed to maintain performance over wide temperature ranges and various loading scenarios, providing a versatile damping solution that adapts to different applications without requiring fundamentally different designs.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables materials with higher specific damping capacity and stiffness, providing efficient damping over a broad range of frequencies and temperatures, reducing material weight and volume while maintaining structural integrity, and allowing for tailored damping responses to various loading situations.
Implementation Method 1
A new material construction is provided that allows enhanced damping performance through means of a bistable or negative stiffness member
Data Source
AI summary
In one embodiment, a vibration control apparatus is provided having a pair of face sheets with a core material in between. The core material comprising a positive stiffness material. A stack comprising a positive stiffness structure in series with a negative stiffness structure is located between the pair of face sheets, in parallel with the core material. The stack may be embedded in the core material. Various embodiments may include multiple stacks in parallel with each other. In some embodiments, the stack may include multiple positive stiffness structures in series with multiple negative stiffness structures. The multiple positive stiffness structures and negative stiffness structures may be interleaved.